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Ahead of print publication
Sclerosing pneumocytoma: A rare benign tumor of lung


1 Department of Pathology and Lab Medicine, All India Institute of Medical Sciences (AIIMS), Bhubaneswar, Odisha, India
2 Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences (AIIMS), Bhubaneswar, Odisha, India

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Date of Submission26-May-2021
Date of Decision03-Jun-2021
Date of Acceptance26-Aug-2021
Date of Web Publication07-Jun-2022
 


How to cite this URL:
Jha S, Sable MN, Mohanty S, Adhya AK, Patra S, Mishra P. Sclerosing pneumocytoma: A rare benign tumor of lung. Indian J Pathol Microbiol [Epub ahead of print] [cited 2023 Feb 5]. Available from: https://www.ijpmonline.org/preprintarticle.asp?id=346858




Dear Editor,

Sclerosing pneumocytoma (SP) is a well-circumscribed benign neoplastic lesion arising in the lung parenchyma with an initial obscure vascular theory behind the cell of origin proposed by Liebow et al.[1] Until recently, it is postulated that the tumor arises from the primitive respiratory epithelium.[2] This forms the rationale for the new nomenclature of SP that is corroborated by the immunohistochemical studies.[3] The pre-operative diagnosis may be challenging and can be overdiagnosed as an adenocarcinoma or underdiagnosed as an infarct.

A 36-year-old woman presented with the non-specific symptoms of dyspepsia and chest pain following which routine hematological, biochemical and radiological examinations were performed. The noncontrast computed tomography revealed a well-defined solid cystic lesion measuring 9.0 cm × 7.5 cm × 6.0 cm located in the upper lobe of left lung [Figure 1]a. The patient underwent left upper lobectomy under general anesthesia and the specimen was sent for histopathological examination. The lobectomy specimen weighed 365.0 g and measured 17.0 cm × 10.0 cm × 6.0 cm, cut section shows a well circumscribed, encapsulated tumor measuring 9.0 cm × 7.5 cm × 6.0 cm. Cut surface of the tumor, is solid, firm, brownish to yellow, and shows vague lobulations [Figure 1]b. Necrosis was not identified grossly. Microscopically the lesion was well circumscribed, pushing the adjacent lung parenchyma [Figure 2]a showed a combination of histological patterns ranging from solid areas to papillae [Figure 2]b that lacked a definitive fibrovascular core, hemorrhagic pattern showing large areas of blood lakes and sclerotic pattern [Figure 2]c. The neoplastic component comprised of dual population of cells, “surface cuboidal cells” and “round stromal cells”, [Figure 2]d. Ectatic spaces filled with red blood cells and lined by cuboidal cells were noted. Extensive areas of sclerosis, calcification [inset [Figure 2]c], hemorrhage and hemosiderin laden macrophages were also seen. Both the population of cells were immunopositive for thyroid transcription factor-1 (TTF-1) [Figure 3]a while only the cuboidal cells showed positivity for pancytokeratin (Pan-CK) and the round were negative for Pan-CK [Figure 3]b and [Figure 3]c. Other markers like synaptophysin, chromogranin, CD31, CD34, S-100, smooth muscle actin (SMA), Melan-A, Human Melanoma Black (HMB-45) and paired box 8 (PAX-8) were negative. A final diagnosis of SP was rendered based on the gross, microscopic features and by the immunohistochemical profile displayed by the tumor cells.
Figure 1: (a) Lung window axial section (NCCT) shows a well-defined soft tissue density solid and cystic in nature located in left upper lobe, pulmonary origin. No bronchial “cut-off”, rather than bronchial splaying is seen. (b) Lobectomy specimen showing a well circumscribed tumor, cut surface is solid, grey tan with foci of hemorrhage and sclerotic bands

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Figure 2: (a) Section shows a relatively well circumscribed tumor (black arrow) and the adjacent compressed lung parenchyma at the periphery. (H and E, 100×). (b) Tumor in papillary pattern showing a dual population of cuboidal surface cells overlying a core of round cells (H and E, 200×). (c) Sclerotic pattern dense areas of stromal collagen are present. (H and E, 200×), inset calcification. (d) Higher magnification of (figure b) cuboidal surface cells (yellow arrow) and round stromal cells (black arrow). (H and E, 400×)

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Figure 3: (a) Surface cuboidal cells and the stromal round cells are positive for thyroid transcription factor-1 (IHC, 100×). (b) Surface cuboidal cells (yellow arrow) are immunopositive for pancytokeratin and the stromal round cells (black arrow) are immunonegative. (IHC, 200×). (c) Another area showing stromal round cells (black arrow) are immunonegative for pancytokeratin and the surface cuboidal cells (yellow arrow) are immunopositive. (IHC, 200×)

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It is a benign tumor with a predilection for women. Many times it is detected incidentally. Usually, it presents as a solitary mass with no definite radiographic findings. Uncommonly chest X-ray can show multiple nodules of varying sizes. Calcification is noted in 41% of cases and nodal metastasis is rare.[4],[5] This divergent radiological picture should be reminisced while formulating the histopathological diagnosis of SP. The diversity of microscopic findings results in a wide range of differential diagnosis including non- neoplastic and neoplastic lesions in small biopsies.[6] The sclerotic pattern in SP may mimic a scar tissue or reparative changes in inflammation and a small biopsy may lead to an underdiagnosis, and a correct diagnosis can only be rendered on resection specimen. Microscopically, it can mimic a well differentiated papillary adenocarcinoma, papillary adenoma, and carcinoid, all of which can present with papillary pattern, posing a diagnostic dilemma especially in biopsy specimen. Dual population of surface cuboidal cells and round stromal cells, lacking cytological atypia, absence of mitotic figures and necrosis favor a benign SP. Papillary adenoma is very challenging in small biopsies and consists of papillary structure containing fibrovascular cores lined by single layer of cuboidal epithelial cells. Nuclear atypia and mitosis are absent, has a low proliferative index and the cells are positive for cytokeratin with no staining in the underlying stroma. Rarely carcinoid tumors may cause a diagnostic pitfall: however monotonous appearance of cells with salt and pepper chromatin with characteristic immunohistochemistry differentiates it from SP. Surgical excision is the treatment of choice. To conclude, SP may pose a diagnostic difficulty both on imaging and histology. Clinicians and pathologists, should be aware of this rare entity since the differential diagnoses is wide and therefore can be an important diagnostic pitfall.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Liebow AA, Hubbell DS. Sclerosing hemangioma (histiocytoma, xanthoma) of the lung. Cancer 1956;9:53-75.  Back to cited text no. 1
    
2.
Chen B, Gao J, Chen H, Cao Y, He X, Zhang W, et al. Pulmonary sclerosing hemangioma: A unique epithelial neoplasm of the lung (report of 26 cases). World J Surg Oncol 2013;11:85.  Back to cited text no. 2
    
3.
Devouassoux-Shisheboran M, Hayashi T, Linnoila RI, Koss MN, Travis WD. A clinicopathologic study of 100 cases of pulmonary sclerosing hemangioma with immunohistochemical studies: TTF-1 is expressed in both round and surface cells, suggesting an origin from primitive respiratory epithelium. Am J Surg Pathol 2000;24:906-16.  Back to cited text no. 3
    
4.
Cheung YC, Ng SH, Chang JW, Tan CF, Huang SF, Yu CT. Histopathological and CT features of pulmonary sclerosing haemangiomas. Clin Radiol 2003;58:630-5.  Back to cited text no. 4
    
5.
Miyagawa-Hayashino A, Tazelaar HD, Langel DJ, Colby TV. Pulmonary sclerosing hemangioma with lymph node metastases. Arch Pathol Lab Med 2003;127:321-5.  Back to cited text no. 5
    
6.
Lovrenski A, Vasilijević M, Panjković M, Tegeltija D, Vučković D, Baroš I, Lovrenski J. Sclerosing pneumocytoma: A ten-year experience at a Western Balkan University Hospital. Medicina 2019;55:27.  Back to cited text no. 6
    

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Correspondence Address:
Pritinanda Mishra,
All India Institute of Medical Sciences, Bhubaneswar - 751 019, Odisha
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_516_21



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